Findings and conclusions from CMV hyperimmune globulin treatment trials

Single-cell analysis of memory B cells from top neutralizers reveals multiple sites of vulnerability within HCMV Trimer and Pentamer

Human cytomegalovirus (HCMV) can cause severe diseases in fetuses, newborns, and immunocompromised individuals. Currently, no vaccines are approved, and treatment options are limited. Here, we analyzed the human B cell response of four HCMV top neutralizers from a cohort of 9,000 individuals. By single-cell analyses of memory B cells targeting the pentameric and trimeric HCMV surface complexes, we identified vulnerable sites on the shared gH/gL subunits as well as complex-specific subunits UL128/130/131A and gO. Using high-resolution cryogenic electron microscopy, we revealed the structural basis of the neutralization mechanisms of antibodies targeting various binding sites. Moreover, we identified highly potent antibodies that neutralized a broad spectrum of HCMV strains, including primary clinical isolates, that outperform known antibodies used in clinical trials. Our study provides a deep understanding of the mechanisms of HCMV neutralization and identifies promising antibody candidates to prevent and treat HCMV infection.

Combined thrombogenic effects of vessel injury, pregnancy and procoagulant immune globulin administration in mice

Background

Pregnant women are at increased risk of thrombotic adverse events. Plasma derived immune globulin (IG) products, which are used in pregnancy for various indications, may contain procoagulant impurity activated coagulation factor XI (FXIa). Procoagulant IG products have been associated with increased thrombogenicity but their effect in pregnancy is unknown.

Methods

Late pregnant (gestation days 17–20) or early lactation (days 1–3) and control female mice were treated with IGs supplemented with human FXIa then subjected to ferric chloride (FeCl₃) vessel injury. Occlusion of blood vessel was assessed by recording blood velocity in the femoral vein for 20 min using doppler ultrasound laser imaging. FXIa dose was selected by the ability to increase thrombin generation in mouse plasma in vitro.

Results

FXIa produced robust thrombin generation in mouse plasma ex vivo. Following FeCl₃ injury, pregnant and non-pregnant mice receiving IG + FXIa exhibited faster reduction of blood velocity in femoral vein compared to IG alone or untreated controls. In vitro, thrombin generation in plasma samples collected after thrombosis in FXIa-treated animals was elevated and could be reduced by anti-FXI antibody.

Conclusions

Our results suggest that intravenously-administered FXIa may contribute to thrombosis at the site of vascular injury in both pregnant and non-pregnant animals.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12959-020-00245-8.

Fetal therapies for cytomegalovirus: What we tell prospective parents

Congenital CMV is the most common congenital infection in the developed world. Infection results in congenital disease ranging from asymptomatic infection to severe neurodevelopmental impairment, and occasionally fetal or neonatal death. Fetal infection can occur through maternal-fetal transmission during primary maternal infection or maternal reactivation or re-infection. Awareness among maternal health care providers and parents is low. The prevention of maternal CMV infection currently relies on hygiene measures, with no effective CMV vaccine or prophylactic therapies. No licensed treatment options are available to prevent maternal-fetal transmission or fetal disease. Hyperimmunoglobulin and valaciclovir have been investigated for prevention of maternal-fetal transmission or fetal treatment, with some evidence supporting consideration of maternal administration of hyperimmunoglobulin or valaciclovir therapy in certain circumstances. This article outlines the clinical evidence regarding proven preventative behavioral measures and experimental hyperimmunoglobulin and valaciclovir therapies, that is structured around common questions asked by pregnant women about CMV infection. It is aimed to help maternity health care providers counsel prospective parents about congenital CMV disease and the preventative and therapeutic strategies currently available.

High level antibodies to TORCH in the IVIG preparation from Taiwanese

BACKGROUND

Congenital TORCH (toxoplasmosis, other viruses [varicella-zoster virus, VZV, etc.], rubella, cytomegalovirus [CMV], Herpes simplex virus [HSV]) infections are major causes of prenatal, perinatal, and postnatal morbidity and mortality. Although treatment or prevention strategies are available for these pathogens, all drugs may not be safe during the pregnancy. The aim of this study is to measure the antibodies (Abs) concentration in the intravenous immunoglobulin (IVIG) preparation to evaluate the therapeutic potential for TORCH infection.

METHODS

We tested the only one commercial IVIG preparation from Taiwanese for the presence of Abs against Toxoplasma gondii, VZV, Epstein-Barr virus (EBV), measles, mumps, rubella, CMV, HSV type 1 (HSV-1), and HSV type 2 (HSV-2) by using enzyme-linked immunosorbent assay or chemiluminescent microparticle immunoassay.

RESULTS

In our study, the median level (range) of anti-CMV immunoglobulin G (IgG) is > 250 (All > 250) (arbitrary unit, AU)/mL, anti-EBV > 200 (All > 200) (relative unit, RU)/mL, anti-HSV > 200 (152.75 to >200) RU/mL, anti-VZV > 5000 (All > 5000) IU/L, anti-measles > 5000 (All > 5000) IU/L, anti-mumps > 200 (156.5 to > 200) RU/mL, anti-rubella 209.8 IU/mL (192.7 to 238.5), and anti-Toxoplasma is 14.05 (12.3 to 16) IU/mL. There was not any immunoglobulin M (IgM) against HSV, VZV, mumps, measles, rubella, CMV, EBV, and Toxoplasma in the "Taiwan Blood Services Foundation" IVIG preparations.

CONCLUSION

There was high activity against T. gondii, VZV, EBV, measles, mumps, rubella, CMV, HSV-1, and HSV-2 in all IVIG batches. Further investigation is warranted to confirm the efficacy of IVIG from Taiwanese for congenital TORCH infections.

Antenatal Cytomegalovirus Infection Screening Results of 32,188 Patients in a Tertiary Referral Center: A Retrospective Cohort Study

OBJECTIVE

The present study aimed to determine cytomegalovirus (CMV) seroprevalence, low and high avidities, and the frequency of polymerase chain reaction (PCR) positivity and neonatal disease in an obstetric population.

MATERIALS AND METHODS

Sera of 32,188 women were tested for CMV IgM and/or CMV IgG between 2008 and 2017. Those with IgM were tested for antibody avidity. Of those with low avidity, PCR was offered.

RESULTS

The frequency of CMV IgG and IgM seropositivity was 62% (16,759/26,854) and 22% (74/32,188). The number with low avidity was 42. In 36/42, the infants were PCR tested for CMV and 9 were CMV positive. Only one infant had signs of congenital CMV infection at the time of birth.

CONCLUSION

This study shows the prevalence of Cytomegalovirus infections in a tertiary referral center in Turkey. Although universal screening is not recommended, it can be helpful for the prevention of congenital infection for seronegative women to be advised to at-risk patients due to high prevalence of CMV exposure.

Cytotect®CP as salvage therapy in patients with CMV infection following allogeneic hematopoietic cell transplantation: a multicenter retrospective study

Cytomegalovirus is one of the main contributing factors to high mortality rates in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT). The main factors of treatment failure are both drug resistance and intolerance. In some cases, Cytotect®CP CMV-hyperimmune globulin is used as salvage therapy. This study aims to investigate the safety and efficacy of Cytotect®CP as a salvage therapy in patients with CMV infection after allo-HCT. Twenty-three consecutive patients received Cytotect®CP for CMV infection after prior CMV therapy. At the time of Cytotect®CP introduction, 17 patients (74%) had developed acute GVHD and 15 patients (64%) were receiving steroid treatment; Cytotect®CP was used as monotherapy (n = 7) and in combination (n = 16). Overall, response was observed in 18 patients (78%) with a median time of 15 days (range: 3-51). Of the 18 responders, 4 experienced CMV reactivation, while 5 responders died within 100 days of beginning treatment. Of these 5 deaths, 4 were due to causes unrelated to CMV. Estimated 100-day OS from the introduction of Cytotect®CP was 69.6%. No statistically significant difference was observed in 100-day OS between responders and non-responders (73.7% vs 50.0%, p = 0.258). Cytotect®CP as salvage therapy is effective and well-tolerated. Given its safety profile, early treatment use should be considered.

Preexisting antibodies can protect against congenital cytomegalovirus infection in monkeys

Human cytomegalovirus (HCMV) is the most common congenital infection and a known cause of microcephaly, sensorineural hearing loss, and cognitive impairment among newborns worldwide. Natural maternal HCMV immunity reduces the incidence of congenital infection, but does not prevent the disease altogether. We employed a nonhuman primate model of congenital CMV infection to investigate the ability of preexisting antibodies to protect against placental CMV transmission in the setting of primary maternal infection and subsequent viremia, which is required for placental virus exposure. Pregnant, CD4+ T cell-depleted, rhesus CMV-seronegative (RhCMV-seronegative) rhesus monkeys were treated with either standardly produced hyperimmune globulin (HIG) from RhCMV-seropositive macaques or dose-optimized, potently RhCMV-neutralizing HIG prior to intravenous challenge with an RhCMV mixture. HIG passive infusion provided complete protection against fetal loss in both groups. The dose-optimized, RhCMV-neutralizing HIG additionally inhibited placental transmission of RhCMV and reduced viral replication and diversity. Our findings suggest that the presence of durable and potently neutralizing antibodies at the time of primary infection can prevent transmission of systemically replicating maternal RhCMV to the developing fetus, and therefore should be a primary target of vaccines to eliminate this neonatal infection.

Impact of Antibodies and Strain Polymorphisms on Cytomegalovirus Entry and Spread in Fibroblasts and Epithelial Cells

Cytomegalovirus (CMV) entry into fibroblasts differs from entry into epithelial cells. CMV also spreads cell to cell and can induce syncytia. To gain insights into these processes, 27 antibodies targeting epitopes in CMV virion glycoprotein complexes, including glycoprotein B (gB), gH/gL, and the pentamer, were evaluated for their effects on viral entry and spread. No antibodies inhibited CMV spread in fibroblasts, including those with potent neutralizing activity against fibroblast entry, while all antibodies that neutralized epithelial cell entry also inhibited spread in epithelial cells and a correlation existed between the potencies of these two activities. This suggests that exposure of virions to the cell culture medium is obligatory during spread in epithelial cells but not in fibroblasts. In fibroblasts, the formation of syncytiumlike structures was impaired not only by antibodies to gB or gH/gL but also by antibodies to the pentamer, suggesting a potential role for the pentamer in promoting fibroblast fusion. Four antibodies reacted with linear epitopes near the N terminus of gH, exhibited strain specificity, and neutralized both epithelial cell and fibroblast entry. Five other antibodies recognized conformational epitopes in gH/gL and neutralized both fibroblast and epithelial cell entry. That these antibodies were strain specific for neutralizing fibroblast but not epithelial cell entry suggests that polymorphisms external to certain gH/gL epitopes may influence antibody neutralization during fibroblast but not epithelial cell entry. These findings may have implications for elucidating the mechanisms of CMV entry, spread, and antibody evasion and may assist in determining which antibodies may be most efficacious following active immunization or passive administration.IMPORTANCE Cytomegalovirus (CMV) is a significant cause of birth defects among newborns infected in utero and morbidity and mortality in transplant and AIDS patients. Monoclonal antibodies and vaccines targeting humoral responses are under development for prophylactic or therapeutic use. The findings reported here (i) confirm that cell-to-cell spread of CMV is sensitive to antibody inhibition in epithelial cells but not fibroblasts, (ii) demonstrate that antibodies can restrict the formation in vitro of syncytiumlike structures that resemble syncytial cytomegalic cells that are associated with CMV disease in vivo, and (iii) reveal that neutralization of CMV by antibodies to certain epitopes in gH or gH/gL is both strain and cell type dependent and can be governed by polymorphisms in sequences external to the epitopes. These findings serve to elucidate the mechanisms of CMV entry, spread, and antibody evasion and may have important implications for the development of CMV vaccines and immunotherapeutics.

A two-step screening approach for the identification of blood donors with highly and broadly neutralizing capacities against human cytomegalovirus

BACKGROUND

Hyperimmunoglobulins are frequently applied for prophylaxis and treatment of human cytomegalovirus (HCMV) infections but were only marginally effective in meta-analyses of clinical studies. This might be partially due to selection of donors rather for total anti-HCMV titers than for neutralizing capacities. To improve efficacy against HCMV infection, we aimed at developing a high-throughput screening method for identification of blood donors with highly and broadly neutralizing capacities.

STUDY DESIGN AND METHODS

Using a Gaussia luciferase-expressing reporter virus, 1000 HCMV immunoglobulin (Ig)G-positive plasma samples with known anti-HCMV immunoglobulin titers were analyzed regarding their neutralization titers against fibroblast and endothelial cell infection. Based on these results, a high-throughput screening was designed. Highly neutralizing plasma samples were further tested 1) by an enzyme-linked immunosorbent assay-based neutralization assay regarding efficiency against different HCMV strains and 2) for their efficiency compared to commercially available hyperimmunoglobulins.

RESULTS

Total anti-HCMV immunoglobulin titers did not correlate with neutralization. Mean neutralization capacities were 15-fold higher in endothelial cells compared to fibroblasts. All plasma samples neutralizing fibroblast infection were at least equally effective against infection of endothelial cells, providing the possibility to simplify our screening method by testing only fibroblasts as target cells with a plasma dilution of 1 in 400. Of the nine tested top HCMV neutralizers, four were broadly effective against different HCMV strains. All nine were significantly superior to hyperimmunoglobulins.

CONCLUSION

Donors with highly and broadly neutralizing capacities can be identified by a two-step high-throughput screening approach. This may provide a basis for improved antibody-based treatment or prophylaxis of HCMV infections.

CMV-specific immune reconstitution following allogeneic stem cell transplantation

Cytomegalovirus (CMV) remains a major contributor to morbidity and mortality following allogeneic haemopoietic stem cell transplant (HSCT) despite widespread use of viraemia monitoring and pre-emptive antiviral therapy. Uncontrolled viral replication occurs primarily in the first 100 d post transplant but this high risk period can extend to many months if immune recovery is delayed. The re-establishment of a functional population of cellular effectors is essential for control of virus replication and depends on recipient and donor serostatus, the stem cell source, degree of HLA matching and post-transplant factors such as CMV antigen exposure, presence of GVHD and ongoing use of immune suppression. A number of immune monitoring assays exist but have not yet become widely accessible for routine clinical use. Vaccination, adoptive transfer of CMV specific T cells and a number of graft engineering processes are being evaluated to enhance of CMV specific immune recovery post HSCT.

Antepartum Screening for Maternal Infection and Immune Status: Is it Time to Broaden Our Routine?

Maternal infections with PVB19, HCV, CMV, and HIV during the antepartum period are important health problems for which the technological capacities for screening and diagnosis during the antepartum period are available. Each of these viruses requires individual consideration for inclusion in screening and for the method of screening during the antepartum period. The availability of efficacious treatments for HCV and CMV, with demonstrable benefits to the mother or fetus, is required before antepartum screening for these infections can be justified. Screening for parvovirus B19 presents a greater concern because it meets most of the features of a screening test (Wilson’s criteria) endorsed by the WHO. There is insufficient evidence to argue strongly for implementation of antepartum PVB19 screening, but the available evidence indicates a need for large studies of potential effectiveness and costs of routine PVB19 screening, either for all pregnant woman or for those at high risk of exposure to PVB19. While the technology to screen for HCV, PVB19, and CMV certainly exists, there must be careful consideration of the downstream implications of routine screening at the level of the individual patient, the general population, and other health care resources, including laboratory infrastructure, before recommending that these infections be screened for routinely in the antepartum period. A strategy for national adoption of an opt-out screening strategy for HIV should be considered.

Comparison of the Cytomegalovirus (CMV) Enzyme-Linked Immunosorbent Spot and CMV QuantiFERON Cell-Mediated Immune Assays in CMV-Seropositive and -Seronegative Pregnant and Nonpregnant Women

Human cytomegalovirus (CMV) infection is a major cause of congenital infection leading to birth defects and sensorineural anomalies, including deafness. Recently, cell-mediated immunity (CMI) in pregnant women has been shown to correlate with congenital CMV transmission. In this study, two interferon gamma release assays (IGRA), the CMV enzyme-linked immunosorbent spot (ELISPOT) and CMV QuantiFERON assays, detecting CMV-specific CMI were compared. These assays were performed for 80 CMV-infected (57 primarily and 23 nonprimarily) pregnant women and 115 controls, including 89 healthy CMV-seropositive pregnant women without active CMV infection, 15 CMV-seronegative pregnant women, and 11 seropositive or seronegative nonpregnant women. Statistical tests, including frequency distribution analysis, nonparametric Kruskal-Wallis equality-of-populations rank test, Wilcoxon rank sum test for equality on unmatched data, and lowess smoothing local regression, were employed to determine statistical differences between groups and correlation between the assays. The CMV ELISPOT and CMV QuantiFERON assay data were not normally distributed and did not display equal variance. The CMV ELISPOT but not CMV QuantiFERON assay displayed significant higher values for primarily CMV-infected women than for the healthy seropositive pregnant and nonpregnant groups (P = 0.0057 and 0.0379, respectively) and those with nonprimary infections (P = 0.0104). The lowess local regression model comparing the assays on an individual basis showed a value bandwidth of 0.8. Both assays were highly accurate in discriminating CMV-seronegative pregnant women. The CMV ELISPOT assay was more effective than CMV-QuantiFERON in differentiating primary from the nonprimary infections. A substantial degree of variability exists between CMV ELISPOT and CMV QuantiFERON assay results for CMV-seropositive pregnant women.

Immunotherapeutic Approaches To Prevent Cytomegalovirus-Mediated Disease

Human cytomegalovirus (CMV) is the major cause of congenital neurological defects in the United States and also causes significant morbidity and mortality for hematopoietic and solid organ transplant patients. Primary infection in immunocompetent individuals rarely causes disease but resolves as a life-long latent infection, characterized by sustained antibody and cellular responses. Despite considerable efforts over the last 40 years to develop live attenuated and subunit vaccines, none is close to receiving regulatory approval. However, there is evidence that antibodies can prevent primary infection and cytotoxic T cells can suppress secondary infection. Prior maternal infection decreases the risk a fetus will contract CMV, while adoptive transfer of virus-specific CD8+ T cells is highly protective against CMV disease in hematopoietic stem cell transplant recipients. As a result, three polyclonal immunoglobulin preparations are approved for clinical use and one monoclonal antibody has reached phase III trials. Enhanced understanding of the viral life cycle from a biochemical perspective has revealed additional targets for neutralizing antibodies in the gH/gL/UL128-131 pentamer. Until an effective vaccine is licensed, passive immunotherapeutics may present an alternative to maintain viral loads and prevent CMV disease in susceptible populations. This review summarizes the progress and potential of immunotherapeutics to treat CMV infection.

Awareness of Cytomegalovirus Infection among Pregnant Women in Geneva, Switzerland: A Cross-sectional Study

BACKGROUND

Cytomegalovirus (CMV) is the most frequent cause of congenital infection and commonly associated with sensorineural deficit. At present, there is neither prophylaxis nor treatment during pregnancy. The objective of this study was to evaluate the level of awareness regarding CMV infection and its consequences in women delivering at the University of Geneva Hospitals (Geneva, Switzerland).

METHODS

The study consisted of a validated questionnaire completed by women in the immediate postpartum period.

RESULTS

The questionnaire was completed by 59% (314/528) of delivering women. Only 39% (123/314) knew about CMV and 19.7% (62/314) had received information about preventive measures. Women were more aware about other congenital diseases, such as toxoplasmosis (87%); human immunodeficiency virus (99%); syphilis (85.5%); rubella (92.3%); and group B Streptococcus (63%). Factors associated with CMV awareness were Swiss nationality, high education level, employment in health care or with children, and being followed by an obstetrician. Regarding quality of information, few were aware of the main CMV complications (deafness, 25.2%; mental retardation, 34.5%). Among those informed about CMV, most (74.6%) knew about preventive measures. Among these, 82.5% thought that these were easily applicable.

CONCLUSIONS

Most women were unaware of CMV infection and its potential risks during pregnancy. It is crucial to improve CMV information given to pregnant women to prevent the risks for the fetus/newborn.

Complete protection of mice against lethal murine cytomegalovirus challenge by immunization with DNA vaccines encoding envelope glycoprotein complex III antigens gH, gL and gO

Human cytomegalovirus infects the majority of humanity which may lead to severe morbidity and mortality in newborns and immunocompromised adults. Humoral and cellular immunity are critical for controlling CMV infection. HCMV envelope glycoprotein complexes (gC I, II, III) represent major antigenic targets of antiviral immune responses. The gCIII complex is comprised of three glycoproteins, gH, gL, and gO. In the present study, DNA vaccines expressing the murine cytomegalovirus homologs of the gH, gL, and gO proteins were evaluated for protection against lethal MCMV infection in the mouse model. The results demonstrated that gH, gL, or gO single gene immunization could not yet offer good protection, whereas co-vaccination strategy apparently showed effects superior to separate immunization. Twice immunization with gH/gL/gO pDNAs could provide mice complete protection against lethal salivary gland-derived MCMV (SG-MCMV) challenge, while thrice immunization with pgH/pgL, pgH/pgO or pgL/pgO could not provide full protection. Co-vaccination with gH, gL and gO pDNAs elicited robust neutralizing antibody and cellular immune responses. Moreover, full protection was also achieved by simply passive immunization with anti-gH/gL/gO sera. These data demonstrated that gCIII complex antigens had fine immunogenicity and might be a promising candidate for the development of HCMV vaccines.

The immunological underpinnings of vaccinations to prevent cytomegalovirus disease

A universal cytomegalovirus (CMV) vaccination promises to reduce the burden of the developmental damage that afflicts up to 0.5% of live births worldwide. An effective vaccination that prevents transplacental transmission would reduce CMV congenital disease and CMV-associated still births and leave populations less susceptible to opportunistic CMV disease. Thus, a vaccination against this virus has long been recognized for the potential of enormous health-care savings because congenital damage is life-long and existing anti-viral options are limited. Vaccine researchers, industry leaders, and regulatory representatives have discussed the challenges posed by clinical efficacy trials that would lead to a universal CMV vaccine, reviewing the links between infection and disease, and identifying settings where disrupting viral transmission might provide a surrogate endpoint for disease prevention. Reducing the complexity of such trials would facilitate vaccine development. Children and adolescents are the targets for universal vaccination, with the expectation of protecting the offspring of immunized women. Given that a majority of females worldwide experience CMV infection during childhood, a universal vaccine must boost natural immunity and reduce transmission due to reactivation and re-infection as well as primary infection during pregnancy. Although current vaccine strategies recognize the value of humoral and cellular immunity, the precise mechanisms that act at the placental interface remain elusive. Immunity resulting from natural infection appears to limit rather than prevent reactivation of latent viruses and susceptibility to re-infection, leaving a challenge for universal vaccination to improve upon natural immunity levels. Despite these hurdles, early phase clinical trials have achieved primary end points in CMV seronegative subjects. Efficacy studies must be expanded to mixed populations of CMV-naive and naturally infected subjects to understand the overall efficacy and potential. Together with CMV vaccine candidates currently in clinical development, additional promising preclinical strategies continue to come forward; however, these face limitations due to the insufficient understanding of host defense mechanisms that prevent transmission, as well as the age-old challenges of reaching the appropriate threshold of immunogenicity, efficacy, durability and potency. This review focuses on the current understanding of natural and CMV vaccine-induced protective immunity.

Models of vertical cytomegalovirus (CMV) transmission and pathogenesis

Despite the considerable clinical impact of congenital human cytomegalovirus (HCMV) infection, the mechanisms of maternal-fetal transmission and the resultant placental and fetal damage are largely unknown. Here, we discuss animal models for the evaluation of CMV vaccines and virus-induced pathology and particularly explore surrogate human models for HCMV transmission and pathogenesis in the maternal-fetal interface. Studies in floating and anchoring placental villi and more recently, ex vivo modeling of HCMV infection in integral human decidual tissues, provide unique insights into patterns of viral tropism, spread, and injury, defining the outcome of congenital infection, and the effect of potential antiviral interventions.

A randomized trial of hyperimmune globulin to prevent congenital cytomegalovirus

BACKGROUND

Congenital infection with human cytomegalovirus (CMV) is a major cause of morbidity and mortality. In an uncontrolled study published in 2005, administration of CMV-specific hyperimmune globulin to pregnant women with primary CMV infection significantly reduced the rate of intrauterine transmission, from 40% to 16%.

METHODS

We evaluated the efficacy of hyperimmune globulin in a phase 2, randomized, placebo-controlled, double-blind study. A total of 124 pregnant women with primary CMV infection at 5 to 26 weeks of gestation were randomly assigned within 6 weeks after the presumed onset of infection to receive hyperimmune globulin or placebo every 4 weeks until 36 weeks of gestation or until detection of CMV in amniotic fluid. The primary end point was congenital infection diagnosed at birth or by means of amniocentesis.

RESULTS

A total of 123 women could be evaluated in the efficacy analysis (1 woman in the placebo group withdrew). The rate of congenital infection was 30% (18 fetuses or infants of 61 women) in the hyperimmune globulin group and 44% (27 fetuses or infants of 62 women) in the placebo group (a difference of 14 percentage points; 95% confidence interval, -3 to 31; P=0.13). There was no significant difference between the two groups or, within each group, between the women who transmitted the virus and those who did not, with respect to levels of virus-specific antibodies, T-cell-mediated immune response, or viral DNA in the blood. The clinical outcome of congenital infection at birth was similar in the two groups. The number of obstetrical adverse events was higher in the hyperimmune globulin group than in the placebo group (13% vs. 2%).

CONCLUSIONS

In this study involving 123 women who could be evaluated, treatment with hyperimmune globulin did not significantly modify the course of primary CMV infection during pregnancy. (Funded by Agenzia Italiana del Farmaco; CHIP ClinicalTrials.gov number, NCT00881517; EudraCT no. 2008-006560-11.).

HCMV infection of human trophoblast progenitor cells of the placenta is neutralized by a human monoclonal antibody to glycoprotein B and not by antibodies to the pentamer complex

Human cytomegalovirus (HCMV) is the major viral cause of congenital infection and birth defects. Primary maternal infection often results in virus transmission, and symptomatic babies can have permanent neurological deficiencies and deafness. Congenital infection can also lead to intrauterine growth restriction, a defect in placental transport. HCMV replicates in primary cytotrophoblasts (CTBs), the specialized cells of the placenta, and inhibits differentiation/invasion. Human trophoblast progenitor cells (TBPCs) give rise to the mature cell types of the chorionic villi, CTBs and multi-nucleated syncytiotrophoblasts (STBs). Here we report that TBPCs are fully permissive for pathogenic and attenuated HCMV strains. Studies with a mutant virus lacking a functional pentamer complex (gH/gL/pUL128-131A) showed that virion entry into TBPCs is independent of the pentamer. In addition, infection is blocked by a potent human neutralizing monoclonal antibody (mAb), TRL345, reactive with glycoprotein B (gB), but not mAbs to the pentamer proteins pUL130/pUL131A. Functional studies revealed that neutralization of infection preserved the capacity of TBPCs to differentiate and assemble into trophospheres composed of CTBs and STBs in vitro. Our results indicate that mAbs to gB protect trophoblast progenitors of the placenta and could be included in antibody treatments developed to suppress congenital infection and prevent disease.

Antibody inhibition of human cytomegalovirus spread in epithelial cell cultures

Anti-cytomegalovirus (CMV) antibodies reduce the incidence of CMV transmission and ameliorate the severity of CMV-associated disease. Neutralizing activity, measured as the ability of antibodies to prevent entry of cell-free virus, is an important component of natural immunity. However, in vivo CMV amplification may occur mainly via spread between adjacent cells within tissues. Thus, inhibition of cell-to-cell spread may be important when evaluating therapeutic antibodies or humoral responses to infection or immunization. In vitro CMV cell-to-cell spread is largely resistant to antibodies in fibroblast cultures but sensitive in endothelial cell cultures. In the present study antibodies in CMV hyperimmuneglobulin or seropositive human sera inhibited CMV cell-to-cell spread in epithelial cell cultures. Spread inhibition activity was quantitated with a GFP reporter assay employing GFP-tagged epithelialtropic variants of CMV strains Towne or AD169. Measurement of spread inhibition provides an additional parameter for the evaluation of candidate vaccines or immunotherapeutics and to further characterize the role of antibodies in controlling CMV transmission and disease.

Cytomegalovirus vaccine strain towne-derived dense bodies induce broad cellular immune responses and neutralizing antibodies that prevent infection of fibroblasts and epithelial cells

Human cytomegalovirus (HCMV), a betaherpesvirus, can cause severe disease in immunosuppressed patients and following congenital infection. A vaccine that induces both humoral and cellular immunity may be required to prevent congenital infection. Dense bodies (DBs) are complex, noninfectious particles produced by HCMV-infected cells and may represent a vaccine option. As knowledge of the antigenicity and immunogenicity of DB is incomplete, we explored characterization methods and defined DB production methods, followed by systematic evaluation of neutralization and cell-mediated immune responses to the DB material in BALB/c mice. DBs purified from Towne-infected cultures treated with the viral terminase inhibitor 2-bromo-5,6-dichloro-1-beta-d-ribofuranosyl benzimidazole riboside (BDCRB) were characterized by nanoparticle tracking analysis (NTA), two-dimensional fluorescence difference gel electrophoresis (2D-DIGE), immunoblotting, quantitative enzyme-linked immunosorbent assay, and other methods. The humoral and cellular immune responses to DBs were compared to the immunogenicity of glycoprotein B (gB) administered with the adjuvant AddaVax (gB/AddaVax). DBs induced neutralizing antibodies that prevented viral infection of cultured fibroblasts and epithelial cells and robust cell-mediated immune responses to multiple viral proteins, including pp65, gB, and UL48. In contrast, gB/AddaVax failed to induce neutralizing antibodies that prevented infection of epithelial cells, highlighting a critical difference in the humoral responses induced by these vaccine candidates. Our data advance the potential for the DB vaccine approach, demonstrate important immunogenicity properties, and strongly support the further evaluation of DBs as a CMV vaccine candidate.

Management of herpesvirus infections

Management of human herpesviruses remains a considerable clinical challenge, in part due to their ability to cause both lytic and latent disease. Infection with the Herpesviridae results in lifelong infection, which can reactivate at any time. Control of herpesviruses is by the innate and adaptive immune systems. Herpesviruses must evade the host innate immune system to establish infection. Once infected, the adaptive immune response, primarily CD8(+) T-cells, is crucial in establishing and maintaining latency. Latent herpesviruses are characterised by the presence of viral DNA in infected cells and limited or no viral replication. These characteristics provide a challenge to clinicians and those developing antiviral agents. The scope of this review is two-fold. First, to provide an overview of all antivirals used against herpesviruses, including their mechanism of action, pharmacokinetics, side effects, resistance and clinical uses. And second, to address the management of each of the eight herpesviruses both in the immunocompetent and immunocompromised host, providing evidence for clinical management and therapeutic options, which is important to the clinician engaged in the management of these infections.

Immune regulation of human herpesviruses and its implications for human transplantation

Human herpesviruses including cytomegalovirus, Epstein-Barr virus, HHV6, HHV7, HHV8, Herpes simplex virus (HSV)-1 and HSV-2 and varicella zoster virus (VZV) have developed an intricate relationship with the human immune system. This is characterized by the interplay between viral immune evasion mechanisms that promote the establishment of a lifelong persistent infection and the induction of a broad humoral and cellular immune response, which prevents the establishment of viral disease. Understanding the immune parameters that control herpesvirus infection, and the strategies the viruses use to evade immune recognition, has been critical in understanding why immunological dysfunction in transplant patients can lead to disease, and in the development of immunological strategies to prevent and control herpesvirus associated diseases.

Preliminary evaluation of the safety and efficacy of standard intravenous immunoglobulins in pregnant women with primary cytomegalovirus infection

Hyperimmune globulins were reported to prevent and treat fetal cytomegalovirus (CMV) infection during pregnancy. Here, we report that infusions of standard human intravenous immunoglobulin significantly increase CMV IgG titers and avidity indexes in pregnant women, paving the way to their use for passive transfer of maternal CMV humoral immunity to fetuses. Preliminary data on perinatal outcomes of the first 67 newborns are encouraging.

Infection control and postexposure prophylaxis for the pregnant healthcare worker

Pregnant health care workers (HCW) may be exposed to pathogens during routine patient care duties. Although they do not seem to be at higher risk for infection compared with nonpregnant HCW, certain infections can be associated with increased maternal morbidity, mortality, and adverse perinatal outcomes. Primary prevention through vaccination is crucial. Medical providers must know which vaccines are safe during pregnancy and which should be postponed until after delivery. Pregnancy should not be a contraindication for certain postexposure prophylaxis regimens after an occupational exposure. Pregnant HCW need to be educated about specific occupational risks and the recommended infection control precautions.

Passive immune neutralization strategies for prevention and control of influenza A infections

Although vaccination significantly reduces influenza severity, seasonal human influenza epidemics still cause more than 250,000 deaths annually. Vaccine efficacy is limited in high-risk populations such as infants, the elderly and immunosuppressed individuals. In the event of an influenza pandemic (such as the 2009 H1N1 pandemic), a significant delay in vaccine availability represents a significant public health concern, particularly in high-risk groups. The increasing emergence of strains resistant to the two major anti-influenza drugs, adamantanes and neuraminidase inhibitors, and the continuous circulation of avian influenza viruses with pandemic potential in poultry, strongly calls for alternative prophylactic and treatment options. In this review, we focus on passive virus neutralization strategies for the prevention and control of influenza type A viruses.

Prenatal neurologic anomalies: sonographic diagnosis and treatment

The low prevalence of fetal CNS anomalies results in a restricted level of exposure to, and limited experience for most obstetricians involved in, prenatal ultrasound. Sonographic guidelines for screening the fetal brain in a systematic way may increase the detection rate of fetal CNS anomalies, thus promoting correct referral to tertiary care centers offering patients a multidisciplinary approach to the condition. The aim of this review is to elaborate on the prenatal sonographic diagnosis and outcome of various CNS malformations. Detailed neurosonographic investigation has become available through high-resolution vaginal ultrasound probes and the development of a variety of 3-dimensional (3D) ultrasound modalities, such as ultrasound tomographic imaging. In addition, fetal magnetic resonance imaging is particularly helpful in the detection of gyration and neurulation anomalies, and disorders of the gray and white matter. Isolated mild ventriculomegaly is a rather common finding with good overall outcome. With an increasing diameter of the atria, however, and especially with the presence of associated malformations, long-term neurodevelopmental and behavioral outcome is disturbed in about 15% or more of cases. In view of recent developments in fetal therapy for neural tube defects, there is a clear need for a high level of ultrasound screening, work-up and counseling in tertiary care centers to identify those cases that might benefit from in utero intervention. The failure of prosencephalic midline induction and development results in midline defects ranging from alobar holoprosencephaly to isolated corpus callosum defects. The detection of callosal abnormaties is enhanced by 3D ultrasound, but counseling on neurodevelopmental outcome remains challenging. The Dandy-Walker spectrum includes isolated megacisterna magna, Blake's pouch cyst, hypoplasia of the vermis and Dandy-Walker malformation. Except for complete agenesis of the vermis associated with fourth ventricle cyst formation, data on long-term outcomes for the various conditions is largely lacking. Congenital cytomegalovirus (CMV) results in the highest incidence of children born with, or developing, long-term neurologic conditions. If proof of fetal infection has been delivered, microcephaly, cortical malformations, and intraparenchymal cysts show a strong correlation with poor outcome. Fetuses with CMV-related ultrasound abnormalities might benefit from maternal transplacental treatment. The aneurysm of the vein of Galen, a vascular malformation of the brain, often results in high cardiac output failure. After neonatal arterial embolization, survival is about 50% with normal neurologic development in 36% of cases. Over 50% of intracranial tumors are teratomata, presenting as fast-growing heterogeneous solid-cystic masses with calcifications. Most intracranial hemorrhages are related to the ventricular system, and prognosis is often poor, particularly in cases involving parenchymal and subdural bleeding. Proliferation disorders of the brain are often characterized by microcephaly. Their etiology is heterogeneous and prenatal diagnosis is often made late in gestation.

Interplay between human cytomegalovirus and intrinsic/innate host responses: a complex bidirectional relationship

The interaction between human cytomegalovirus (HCMV) and its host is a complex process that begins with viral attachment and entry into host cells, culminating in the development of a specific adaptive response that clears the acute infection but fails to eradicate HCMV. We review the viral and cellular partners that mediate early host responses to HCMV with regard to the interaction between structural components of virions (viral glycoproteins) and cellular receptors (attachment/entry receptors, toll-like receptors, and other nucleic acid sensors) or intrinsic factors (PML, hDaxx, Sp100, viperin, interferon inducible protein 16), the reactions of innate immune cells (antigen presenting cells and natural killer cells), the numerous mechanisms of viral immunoevasion, and the potential exploitation of events that are associated with early phases of virus-host interplay as a therapeutic strategy.

Passive immunization: the forgotten arm of immunologically based strategies for disease containment

Passive immunization provides temporary protection in a naïve subject who has been exposed to an infectious pathogen when vaccination is unavailable or has not been given before exposure. Despite the recent attention that has been given to adult-directed vaccines, antibody-based therapeutic strategies have received little discussion yet remain an important part of infectious disease containment. This review examines some of the more common clinical situations in which an obstetrician-gynecologist may need to have expertise related to passive immunization. Potential future uses for this modality are presented.

Modeling of human cytomegalovirus maternal-fetal transmission in a novel decidual organ culture

Human cytomegalovirus (HCMV) is the leading cause of congenital infection, associated with severe birth defects and intrauterine growth retardation. The mechanism of HCMV transmission via the maternal-fetal interface is largely unknown, and there are no animal models for HCMV. The initial stages of infection are believed to occur in the maternal decidua. Here we employed a novel decidual organ culture, using both clinically derived and laboratory-derived viral strains, for the ex vivo modeling of HCMV transmission in the maternal-fetal interface. Viral spread in the tissue was demonstrated by the progression of infected-cell foci, with a 1.3- to 2-log increase in HCMV DNA and RNA levels between days 2 and 9 postinfection, the expression of immediate-early and late proteins, the appearance of typical histopathological features of natural infection, and dose-dependent inhibition of infection by ganciclovir and acyclovir. HCMV infected a wide range of cells in the decidua, including invasive cytotrophoblasts, macrophages, and endothelial, decidual, and dendritic cells. Cell-to-cell viral spread was revealed by focal extension of infected-cell clusters, inability to recover infectious extracellular virus, and high relative proportions (88 to 93%) of cell-associated viral DNA. Intriguingly, neutralizing HCMV hyperimmune globulins exhibited inhibitory activity against viral spread in the decidua even when added at 24 h postinfection-providing a mechanistic basis for their clinical use in prenatal prevention. The ex vivo-infected decidual cultures offer unique insight into patterns of viral tropism and spread, defining initial stages of congenital HCMV transmission, and can facilitate evaluation of the effects of new antiviral interventions within the maternal-fetal interface milieu.

Cytomegalovirus antivirals and development of improved animal models

INTRODUCTION

Cytomegalovirus (CMV) is a ubiquitous pathogen that establishes a lifelong asymptomatic infection in healthy individuals. Infection of immunesuppressed individuals causes serious illness. Transplant and AIDS patients are highly susceptible to CMV leading to life-threatening end-organ disease. Another vulnerable population is the developing fetus in utero, where congenital infection can result in surviving newborns with long-term developmental problems. There is no vaccine licensed for CMV and current antivirals suffer from complications associated with prolonged treatment. These include drug toxicity and emergence of resistant strains. There is an obvious need for new antivirals. Candidate intervention strategies are tested in controlled preclinical animal models but species specificity of human CMV precludes the direct study of the virus in an animal model.

AREAS COVERED

This review explores the current status of CMV antivirals and development of new drugs. This includes the use of animal models and the development of new improved models such as humanized animal CMV and bioluminescent imaging of virus in animals in real time.

EXPERT OPINION

Various new CMV antivirals are in development, some with greater spectrum of activity against other viruses. Although the greatest need is in the setting of transplant patients, there remains an unmet need for a safe antiviral strategy against congenital CMV. This is especially important as an effective CMV vaccine remains an elusive goal. In this regard, greater emphasis should be placed on suitable preclinical animal models and greater collaboration between industry and academia.

Cytomegalovirus infections during pregnancy

PURPOSE OF REVIEW

To review current prenatal diagnosis and management of congenital cytomegalovirus (CMV) infections with emphasis on maternal screening and available interventions.

RECENT FINDINGS

Recent findings include an enhanced understanding of the epidemiology, pathogenesis, and treatment of CMV infections; a knowledge of high-risk women particularly those with chronic exposure to a young child in the home; the availability of accurate methods for the serologic diagnosis of a primary CMV infection using either single or serial blood samples; accurate methods for the diagnosis of fetal infection via amniotic fluid; sensitive fetal and placental indicators for neonatal outcomes, and the availability of potentially effective interventions such as hygienic intervention and CMV hyperimmune globulin.

SUMMARY

These findings suggest that serologic testing for CMV during pregnancy may be appropriate either using one-time testing or serial serologic testing throughout the first two trimesters of pregnancy and that education of pregnant women about CMV is necessary so that they can asses their risk and make informed choices about serologic screening.

Early inhibitors of human cytomegalovirus: state-of-art and therapeutic perspectives

Human cytomegalovirus (HCMV) infection is associated with severe morbidity and mortality in immunocompromised individuals, mainly transplant recipients and AIDS patients, and is the most frequent cause of congenital malformations in newborn children. To date, few drugs are licensed for the treatment of HCMV infections, most of which target the viral DNA polymerase and suffer from many drawbacks, including long-term toxicity, low potency, and poor bioavailability. In addition, the emergence of drug-resistant viral strains is becoming an increasing problem for disease management. Finally, none of the current anti-HCMV drugs have been approved for the treatment of congenital infections. For all these reasons, there is still a strong need for new anti-HCMV drugs with novel mechanisms of action. The first events of the virus replication cycle, including attachment, entry, immediate-early gene expression, and immediate-early functions—in particular that of Immediate-Early 2 protein—represent attractive targets for the development of novel antiviral compounds. Such inhibitors would block not only the expression of viral immediate-early proteins, which play a key role in the pathogenesis of HCMV infection, but also the host immunomodulation and the changes to cell physiology induced by the first events of virus infection. This review describes the current knowledge on the initial phases of HCMV replication, their validation as potential novel antiviral targets, and the development of compounds that block such processes.

Fetal medicine and treatment

Fetal medicine covers a broad spectrum of conditions that can be diagnosed before birth. Different disorders will require different treatment strategies and there is often an important ontogenetic aspect on how and when treatment can be implemented. Due to the limited availability there is a general lack of knowledge on how pharmacotherapy can be provided in the most efficient way. Until recently most knowledge about how different drugs are transferred and metabolized in the human fetus is based on very limited observational studies on concentrations of drugs in fetal blood and other fetal compartments. It might be that the rapid development of other non-invasive methods for fetal diagnostics such as isolation of fetal DNA and RNA in maternal serum, NMR imaging and other techniques could in the future be explored in fetal pharmacotherapy. Introduction of new treatment strategies are often based on extrapolation from experience in neonates and adults. However some fetal conditions are very specific for this time period in life. This especially entails disturbances in development as malformations, early growth restriction and several congenital disorders. Here it might be required to introduce new treatment strategies without any previous experience in humans. Example of this ethical dilemma is gene therapy for lung growth in severe cases of diaphragmatic hernia and early growth restriction. The risk-benefit issues need to be discussed in all these alternatives. However, it is likely that the concept of the human fetus as a potential patient is still in its infancy and with an improved understanding about fetal patho-physiology there will be a continued need for better knowledge of pharmacotherapy during this crucial time period in life.